A lengthy argument due to Caticha [1]}[2]}, which is beyond the scope of this thesis, narrows the space of functions \(G\)  to those of just two variables. In particular, \(G = G(\xi (a|c),\xi (b|ac))\) .Essentially, one considers all possible choices of functions for \(G\) , ranging from two inputs to all four. By examining certain clever special choices of inputs, one can eliminate all but one of the functions as the others demonstrate clearly irrational results (such as, for example \(G = \) constant).
